Talk:24-hour clock/Archive 2

Exaggerated claim & falsehood about ISO 8601
We should not describe ISO 8601 as "the" international standard for writing dates and times. There are many international standards for this purpose, ISO 8601 is only one of them. Furthermore, placing it in the lead implies that lots of people actually pay attention to the standard; I see little evidence that people other than computer programmers and perhaps high-volume manufacturers pay attention to it. Jc3s5h (talk) 15:42, 2 April 2014 (UTC)

In addition, it is false to state that the format of 24 hour clocks is specified by ISO 8601. ISO 8601 specifies its own format for 24 hour time, but other formats exist (without a colon, with or without 0 padding to the left, hands on a 24 hour analog clock, etc.) Jc3s5h (talk) 15:48, 2 April 2014 (UTC)


 * ISO 8601 is undeniably an international standard, and the article at the moment does not say "the" international standard.
 * What are the other international standards are there for writing dates and times? It may be pertinent to mention them in the article.
 * ISO 8601 does specify "24-hour timekeeping system", which - for the purposes of this article - is fundamentally the same thing as "the convention of time keeping in which the day runs from midnight to midnight and is divided into 24 hours, indicated by the hours passed since midnight, from 0 to 23" (and the standard does mandate counting the hours that way).
 * Although I make no comment about how many people "pay attention to the standard", you might have a point about it not belonging in the lead paragraph - is it worth creating a separate section for it? (The answer may depend on what other international standards there are, and whether or not they also specify 24-hour time.) Mitch Ames (talk) 12:01, 3 April 2014 (UTC)


 * There are other international standards for time and date formats. The POSIX standard is described in a good post as well as more formal documents. (That standard is for within computers, not for display to humans, but some people have the same opinion about ISO 8601).


 * , updated by and RFC 2822 provide a format for Internet messages, such as email. It uses English abbreviations for day and month names, but since there are a number of countries where English is the main language, it can still claim to be international.


 * Certainly the time format specified within ISO 8601 is a 24 hour format. However, a version of the article from late March stated "[24 hour time] is the most commonly used time notation in the world today, and is the international standard (ISO 8601) notation for time of day." This implies the notation within ISO 8601 is the only acceptable notation. A version from April 2 states 24 hour time "is prescribed by the international standard Jc3s5h (talk) 13:00, 3 April 2014 (UTC)
 * Earlier version may have been less than ideal, but are you happy with the current words "and is used by international standard ISO 8601"? So far as I can tell, they are literally true and don't make unwarranted implications about 8601.
 * Should we take 8601 out of the lead paragraph, and instead create a new section "Standards", in which we list standards (international and otherwise) that specify the 24-hour system? I think is worth explicitly stating in the article (not necessarily the lead) that the 24-hour system is mandated by some specific standards. Although "the format for writing 24 hour time" may not be standardized, the use of the 24-hour system (instead of the 12-hour clock) is mandated by some standards.
 * Do other editors have an opinion? Mitch Ames (talk) 14:02, 3 April 2014 (UTC)

Navy Correspondence Manual
U.S. Navy and U.S. Marine Corps use 0001 to 2400 SECNAV M-5216.5 Department of the Navy Correspondance Manual dated March 2010, Chapter 2, Section 5 Paragraph 15. Expressing Military Time. (page 18) PerkinsC (talk) 20:08, 7 April 2014 (UTC)
 * i placed the text already, but it does NOT look right where it is, please fix... there are two places where this information might be relevant, but i put it in the part that references the joint Communication protocol as the usages appear to contradict each other PerkinsC (talk) 20:36, 7 April 2014 (UTC)
 * the Correspondance Manual covers everything from eMail traffic to hard Copy letters that are sent through the mail. the Exact Text Follows

15. ExpressingMilitary Time. Express military time in four digits based on the 24-hour clock. The time range is 0001 to 2400. The first two digits are the hour after midnight and the last two digits are the minutes. Do not use a colon to separate the hour from the minutes. EXAMPLE: 6:30 am in civilian time is 0630 in military time 3:45 pm in civilian time is 1545 in military time" PerkinsC (talk) 20:49, 7 April 2014 (UTC)

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Can the "hundred" be dropped?
Can the "hundred" be dropped when saying the time in 24-hr notation? For example, is it okay to say "thirteen" instead of "thirteen hundred"? Thanks. 24.150.217.182 (talk) 16:24, 9 July 2017 (UTC)
 * I live in the UK (and have lived in other English-speaking countries) and we use 24-hour notation regularly. But never verbally or written out in words (only numbers, i.e. 21:15 is spoken as "nine fifteen PM" or "quarter past nine"). What you are talking about is military time (distinct from normal 24-hour notation), and there are regulations on how to use it verbally. I've only seen it being used in films and fiction books. I hope that helps you as you search for your answer. This might help: http://www.marforres.marines.mil/Portals/116/Docs/G-1/AAU/AAUDocuments/CORRESPONDENCE%20MANUAL.pdf --BurritoBazooka Talk Contribs  17:46, 9 July 2017 (UTC)
 * the "hundred" is to indicate that it is 00 minutes... PerkinsC (talk) 19:32, 5 September 2017 (UTC)
 * Although "hundred" is sometimes employed colloquially (a hangover from military usage, I suspect) -- e.g. "If you miss the fifteen thirty-nine, there's another train at sixteen hundred" -- the BBC World Service announces programmes as starting at "seven hours", "fourteen hours", "twenty-one hours" etc. -- Picapica (talk) 16:51, 12 May 2018 (UTC)

Leading zeros?
Do you have to include leading zeros in the 24-hour clock? I am not talking about military time, i am talking about the regular 24-hour clock. I hate leading zeros and can they be dropped? For example, is it okay to say 9:00 instead of 09:00? Thanks! 24.150.217.182 (talk) 14:55, 30 July 2017 (UTC)
 * For the record, these questions should generally be asked at the reference desk. Prinsgezinde (talk) 17:59, 21 January 2018 (UTC)
 * Leading zeros are always employed in four-figure notation -- e.g. "There are flights at 0630, 0955, 1315, and 1645". They may be omitted, however, when the hours are separated from the minutes by punctuation (a colon -- or, in the UK as often as not -- a period): 6:30 or 9.55. Nevertheless, the use of leading zeros is good practice, in making it quite clear that 06:30 or 09.55 are morning times. -- Picapica (talk) 17:04, 12 May 2018 (UTC)

Times of 24:01 and later (after midnight) are used in the United States, also
I'm glad the main article has a section about times notated as being after 24:00, such as 25:08 meaning 1:08 AM on the following day. I have seen this used in at least two US cities in multiple contexts, but always in reference to a business or other entity that operates on a daily cycle, but the operational day ends after midnight. For instance, I worked with a factory where the operational day went from 06:00 (6 AM) until 26:00 (2 AM on the following day), but the workers on-shift at 25:59 are always the same people who were on-shift at 23:30, and that is important to remember. It should be easily visible in all of the logs, and so on. Hospitals use 24-hour clocks for a similar reason, so that it doesn't roll over at noon (which is usually not a shift change), but hospitals are always open around-the-clock, so it needs to roll over somewhere, and the sensible default is midnight. A factory that closes at 2 AM can roll over at some ill-defined time between closing and opening. If you lock up a bit late, you can record that as 26:05. If you arrive a bit early, you can record that as 05:50. In both cases, you are outside the operational hours, but your choice of notations shows whether you are the first shift arriving early or the final shift leaving late. I have no citations, this entire article would be better if it had citations and were longer and more nuanced, I just have some forbidden Original Research. Fluoborate (talk) 05:47, 13 May 2018 (UTC)

Zulu time
The convention of adding "Z" to 24-hour time notation when UTC is used is not limited to military use; it is used elsewhere too. This is often done whether or not there is a colon between the hours and minutes. --Zzo38 (talk) 04:22, 22 October 2018 (UTC)

US EST "R"
Just checking re:

"Military time zones are lettered and thus given word designations via the NATO phonetic alphabet. For example, 6:00 a.m. US Eastern Standard Time (UTC−5) would be written "0600R" and spoken "zero six hundred Romeo". "

So US EST is designated R? (The other designations are spelled out as such, is why I ask.)

Thanks in advance --Philologia 15:31, 9 January 2019 (UTC)

Deleting of fraudulent website from external links
Hello,

my name is Jano and I would like to ask you to delete external link "Military Time Chart" to website http://www.militarytime.site/.

The reason why I ask you for this is that the owner of this wesbite stole images from my website: https://spacedoxie.com/military-time-chart/

You can check it. I already wrote him but he does not reply or even delete my images.

Please replace his backlink by link to my wesbite which is all about Military time (https://spacedoxie.com/) or with some other, trustful website about Military time according to your consideration.

Thank you so much for your help

Have a nice day

Jano — Preceding unsigned comment added by Chochi7 (talk • contribs) 10:20, 27 February 2019 (UTC)


 * I deleted the external link because it does not provide information that isn't already apparent from the Wikipedia article and is overly wordy. No need to decide who created the information first. Jc3s5h (talk) 10:30, 27 February 2019 (UTC)

Ok, it sounds reasonable, thank you. But just a question, is it possible to add there my website? It contains explanations of conversions of all full and half hours from military time to standard time and much more informative articles with unique tools for converting time. I mean I think it is really helpful so could make sence to add it. Thank you for answer — Preceding unsigned comment added by Chochi7 (talk • contribs) 10:54, 27 February 2019 (UTC)


 * See WP:ELNO number 11, which explains that personal websites should not be added. Also most people can and do convert mentally once they find out what 24 time is; computer tools are not worth the trouble. Jc3s5h (talk) 13:37, 27 February 2019 (UTC)

Just for the record: someone again tried to add links to the aforementioned website (see edits done bewtween 11:33 and 11:48 on 19 April 2019). Ngfio (talk) 18:04, 19 April 2019 (UTC)

Difference between UTC and some senses of GMT
In this edit [[User:Groogle|Groogle] made the change "For other purposes there may be a difference of about up to a second ." If you read the cited article, you will see that some of the other purposes in which the term GMT is used are While, at present, the difference |UT1&minus;UTC| <= 0.9 s, the difference between some of the other meanings of GMT and UT1 may be greater.
 * Classical measurements of GMT carried out at the Airy meridian instrument of the Royal Greenwich Observatory (which is no longer possible because that site is now a museum).
 * These measurements were carried out on both the Sun and on stars; measurements of the Sun are less precise.
 * Mean observations of a number of observatories around the world, each with equipment similar to the Royal Greenwich Observatory
 * The UT1 time scale, progressively refined since 1955.

I suggest the phrase "may be" in the text before the change allows for the possibility the difference is less than 1 second, or even 0, at any given moment. Jc3s5h (talk) 12:46, 24 July 2019 (UTC)

Use of pm with 24-hour time
I am noticing multiple uses of 24-hour time with "am" and "pm" across the world, for example, 21:00 pm or 21:00pm or 21pm in place of the expected 21:00 or 9 pm. I have found examples of this usage on web pages from across the world:
 * http://www.cpwy.org/doc/3103.pdf
 * https://yogawithjosh.com/product/slow-flow-wednesday-1800-1900pm-gmt-4/
 * https://tucsonerhospital.com/wp-content/uploads/2021/01/RN-Job-Posting.pdf
 * https://www.reddit.com/r/superstarsmtown/comments/9thby1/scheduled_server_maintenance_1800pm_1900pm_kst/
 * https://www.juicecrafters.com/instorepickup/index/
 * https://stayhappening.com/e/wsa-x-wfw-catwalk-show-ba-fashion-18-00pm-19-00pm-E3LUSGP98SNE
 * https://www.ccht.org.uk/for-residents/activity-and-events-calendar/social/bingo-at-philip-house/
 * https://m.facebook.com/story.php?story_fbid=110178061180486&id=107317184799907&m_entstream_source=timeline&__tn__=%2As%2As-R
 * https://igeniuskid.com/events/pre-genius/
 * https://lfsolutions.net/our-presence/
 * https://m.facebook.com/SKbarbershopvarna/photos/a.209040537146444/209040583813106/

I believe this usage belongs in this article on the 24-hour clock, but have been unable to find any discussions of it to establish notability/that it is not simply original research on my part. I am mentioning it here so that hopefully someone will find a discussion of this phenomenon from a verifiable source.

157.131.246.107 (talk) 00:51, 12 September 2021 (UTC)


 * On a different topic (about whether AD stands for "after death" in year numbering) other editors would not accept my word that this mistake was widespread enough to mention in an article. It wasn't until I found a book which commented on it being a common error that it could be mentioned in the article. Jc3s5h (talk) 02:02, 12 September 2021 (UTC)